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Genetics Test 5 > 35 Phylogeny > Flashcards

35 Phylogeny Flashcards

1
Q

Evolution is…

A

genetic changes in the composition of a population including…

  • emergence of species
  • divergence of species
  • extinction of species
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2
Q

Evolution involves…

A

variation
heredity
selection

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3
Q

Variation must be…

A

heritable so it is passed onto the next generation

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4
Q

Change in evolution must be…and occur in…

A

genetic

a population, not individual

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5
Q

Does the individual or gene pool evolve?

A

gene pool

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6
Q

2 step process of genetic change in a population

A
  • genetic change occurs - ex. mutation or recombination

- different alleles increase or decrease in frequency in the gene pool

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7
Q

mutation causes…

A

new alleles

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8
Q

recombination causes

A

new combinations of alleles

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9
Q

diversity

A

different alleles are present at a locus in a population

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10
Q

classical hypothesis

A
  • organisms need low levels of heterozygosity so they are well-adapted to their environment
  • selection favors well adapted genotypes
  • each individual should be well adapted to its environment and therefore there should be little variation
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11
Q

balance hypothesis

A
  • organisms need high levels of heterozygosity so they can respond to changes in the environment
  • a successful population would have lots of variability to produce a variety of phenotypes and allow adaptation to a changing environment
  • there should be a lot of variability in the population
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12
Q

neutralist theory

A
  • many mutations are neutral
  • this causes polymorphisms
  • these are maintained since neither form has an advance and mutant types are not affected by selection
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13
Q

Two proteins with slightly different amino acid sequences both have proper level of function

this supports…

A

neutralist theory

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14
Q

selectionist theory

A

many poplymorphisms are maintained in the population due to selection

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15
Q

two forms of protein may allow for optimum performance over a range of cellular conditions

this supports…

A

selectionist theory

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16
Q

heterozygous sickle cell where an individual has protection against malaria but does not get sickle cell supports

A

selectionist theory

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17
Q

nearly neutral model

A

in some cases a heterozygous condition is advantageous but most mutations are neutral

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18
Q

factors effecting diversity within a population

A
  • migration
  • mutation
  • genetic drift
  • inbreeding
  • natural selection
  • recombination
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19
Q

migration and mutation

A

introduces variability within populations by introducing new alleles

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20
Q

genetic drift

A

decreases diversity within populations as alleles are fixed and lost

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21
Q

inbreeding

A

increases homozygous types with decrease of heterozygous types - no change in allele frequency

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22
Q

natural selection

A

can increase or decrease variability within population depending on the type of selection

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23
Q

recombination

A

increase variability

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24
Q

pecies

A

a group of individuals that actually or potentially interbreed in nature

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25
Q

reproductive isolation

A

species become distinct when they no longer exchange genes

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26
Q

Why does reproductive isolation occur?

A
  • individuals does choose to mate with each other or cannot mate with each other
  • their progeny are sterile or inviable
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27
Q

prezygotic barriers to speciation

A
  • occur before mating occurs

- oganisms chose not to or cannot mate with each other

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28
Q

postzygotic barriers to speciation

A
  • progeny are sterile or inviable
29
Q

biological species concept

A

members of a species are capable of inter-mating and producing fertile progeny

30
Q

examples of prezygotic barriers to speciation

A
  • ecological - differences in habitat
  • temporal - reproduction takes place at different times
  • mechanical - anatomical differences prevent copulation
  • behavioral - differences in mating behavior
  • genetic - gametes are incompatible
31
Q

examples of postzygotic barriers to speciation

A
  • hybrid inviability
  • hybrid sterility
  • hybrid breakdown
32
Q

hybrid inviability

A

hybrid zygote does not survive to reproduction

33
Q

hybrid sterility

A

hybrid is sterile

34
Q

hybrid breakdown

A

F1 hybrids are viable and fertile but F2 are inviable or sterile

35
Q

allopatric speciation

A

geographic barrier initiates speciation by blocking gene flow/barrier to reproduction

36
Q

example of allopatric speciation

A

Darwin’s finches

37
Q

Darwin’s Finches

A
  • 14 species evolved from a single ancestral species
  • the ancestral species migrated to the Galapaogs Islands
  • as new islands were produced, birds migrated to them
  • the ocean formed a geographical barrier
  • over time, behavioral isolation occurred leading to differences in song type
38
Q

sympatric speciation

A

arises within a single interbreeding population without geographical barriers to gene glow

39
Q

example of sympatric speciation

A

races of apple maggot fly

  • disruptive selection depending on resource environment
  • original fly fed on hawthorn tree, mutation allowed it to feed on apples
  • those with the mutation mated on apple trees leading to reproductive isolation
40
Q

allopolyploidy

A
  • hybridization leads to this
  • mechanism for sympatric speciation
  • 2 species mate producing sterile F1
  • chromosome doubling occurs producing fertile plant with two copies of each chromosome
41
Q

anagenesis

A

evolution within a lineage over time

42
Q

cladogenesis

A

splitting of one lineage into two

  • once occurs, the two branches evolve separately from each other
43
Q

cladogenesis leads to…

A

biological diversity since more species exist at the same time

44
Q

phylogenetics

A

study of the relationship among and between species, individuals, or genes/alleles based on their characteristics

constructed by inferring evolutionary relationships among present day organisms

45
Q

What can be measured to evaluated evolutionary divergence

A
  • morphology
  • chromosome structure
  • protein sequences
  • DNA sequences
46
Q

inversions suppress..

A

crossover since gametes produced through recombination are not viable

47
Q

selection tends to favor…

A

the individuals who are homozygous for each allele and does not favor heterozygotes

48
Q

paralogs

A

homologous sequences in the same species

arrive through gene duplication

49
Q

orthologs

A

homologous sequences found in different species

50
Q

compare orthologous and paralogous sequences to evaluate…

A

the amount of change over time between and within species

51
Q

Gene duplication allows

A

genes to evolve different functions

52
Q

ex of gene duplication

A

successive gene duplications occurred resulting in different chains of the immune system genes and the myoglobin gene

53
Q

the highest rate of nucleotide substitution are in

A

sequences that have the least effect on protein function

54
Q

molecular clock

A

the relationship between the constant mutation rate in the change of DNA/amino acid sequence and the differences in sequence between present day organisms that assumes a linear rate of mutation over time

55
Q

the relative values of the rate of nucleotide substitution per site per year correlate in what way with their function

A
  • negatively
  • such that mutations that greatly affect the sequence or function of protein are less common than those that do not have such a large effect on protein function
56
Q

the lowest number of nucleotide substitutions occur as…

A

the nonsynonymous changes

they are rate

57
Q

the highest number of changes that occur are…

A

synonomous changes

58
Q

the promoter is in the…

A

5’ flanking

59
Q

pseudogenes

A

areas of the DNA that do not code for functional genes but have similar sequences to the function genes
produced by gene duplication and accumulate mutations without causing a disruption in normal function

60
Q

operational taxonomic units

A

can be a species or a strain of a virus or different alleles within a species

examined in phylogenetic trees to show the degrees of similarity

61
Q

rooted tree

A

have common ancestor for all terminal nodes

the distance between OTUS is known and the order of divergence is inferred by comparing to an OTU that is an outgroup

62
Q

outgroup

A

an OTU that is known to have diverged earlier than all of the other OTUs

63
Q

unrooted trees

A

do not have a common ancestor

only the distance between OTUs is known not the order of divergence

64
Q

terminal nodes

A

the nodes at the end of the tree

65
Q

internal nodes

A

nodes located within the middle of the tree

66
Q

DNA sequence alignment

A

identification of homolgous genes and properly aligning their sequence to determine an accurate tree

67
Q

distance approach

A
  • computing difference to infer relationships based on overall similarity of organisms by typically using multiple phenotypic characterisistics or gene sequence
68
Q

UPGMA

A

unweighted pair group method with arithmetic mean

method of constructing a phylogenetic tree based on computing difference in DNA sequences

Genetics Test 5 (5 decks)

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